1. Field
The present invention relates to a lithographic apparatus and a method for manufacturing a device.
2. Related Art
A lithographic apparatus is a machine that applies a desired pattern onto a substrate or part of a substrate. A lithographic apparatus can be used, for example, in the manufacture of flat panel displays, integrated circuits (ICs) and other devices involving fine structures. In a conventional apparatus, a patterning device, which can be referred to as a mask or a reticle, can be used to generate a circuit pattern corresponding to an individual layer of a flat panel display (or other device). This pattern can be transferred onto all or part of the substrate (e.g., a glass plate), by imaging onto a layer of radiation-sensitive material (resist) provided on the substrate.
Instead of a circuit pattern, the patterning means can be used to generate other patterns, for example a color filter pattern or a matrix of dots. Instead of a mask, the patterning device can comprise a patterning array that comprises an array of individually controllable elements. The pattern can be changed more quickly and for less cost in such a system compared to a mask-based system.
A flat panel display substrate is typically rectangular in shape. Lithographic apparatus designed to expose a substrate of this type can provide an exposure region that covers a full width of the rectangular substrate, or which covers a portion of the width (for example half of the width). The substrate can be scanned underneath the exposure region, while the mask or reticle is synchronously scanned through the beam. In this way, the pattern is transferred to the substrate. If the exposure region covers the full width of the substrate then exposure can be completed with a single scan. If the exposure region covers, for example, half of the width of the substrate, then the substrate can be moved transversely after the first scan, and a further scan is typically performed to expose the remainder of the substrate.
Where a desired dose pattern is to be built up from pixels imaged by an array of individually controllable elements, an initial step in the data processing procedure may be to rasterize the desired dose pattern into a bitmap form. However, when high concentrations of device features are needed, the bitmap form is likely to represent a very large amount of data, which can be difficult and/or expensive to process and/or store.
One approach is to compress the bitmap data, but this presents many challenges, including that of providing hardware capable of online decompression and of dealing with variations in the nature of the requested pattern and its compression/decompression properties. For a given cost of apparatus, it may be necessary to constrain the types of patterns that can be formed and/or accept that highly complex patterns will be produced relatively slower, both of these alternatives representing undesirable limitations for a user of the lithography device.
Therefore, what is needed is a system and method utilizing an improved data compression/decompression system for a lithographic apparatus.